Method of cleaning oil wells



w. F. MUEHL. 7 METHOD OF CLEANING OIL WELLS.

APPLICATION FILED JULY 22,1920.

Patented Mar. 28, 1922.

A TTOR/VEV PATENT QFF'HCE.

WILLIAM F. MUEHL, OF KANSAS CITY, MISSOURI.

METHOD OF CLEANING OIL WELLS.

Il,dl,827.

Specification of Letters Patent.

Patented Mar. 28, 1922.

Application filed July 22, 1920. Serial No. 398,218.

To all whom it may concern.

Belt known that 1, WILLIAM F. MUEHL, a citizen of the United States, residing at Kansas City, in the county of Jackson and State of Missouri, have invented certain new and useful Improvements in Methods of Cleaning Oil Wells; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying'drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

This invention relates to a method of cleaning oil wells.

After oil wells have been producing for a time, the walls, (that is, the screen-like lining in soft sand wells or in hard sand wells, the sands) not infrequently become clogged with accumulations of some or all of the following substances: calcium, (generally in the form of lime) parailin, bitumen, or asphaltum, the result being that the well ceases to reduce.

n those wells in which a reticulated or foraminous lining is provided, openings in the lining in time become closed and in those wells known as hard sand wells in which no reticulated lining is used, the sands become clogged.

Various methods have been resorted to for relieving-the wells of these objectionable ac cumulations but insofar as I am advised prior attempts have been unsatisfactory on account of the difficulty or ridding the sands in the soft sand wells of the residuary accumulations. l have provided a method whereby the walls of the hard sand wells and the walls and the meshes in the screens used in soft sand wells may be freed from the objectionable matter in an eiiicient manner. According to my invention, any or all of the above accumulation may be dissipated and the clogged well and screens relieved so that the flow of the oil from the surrounding strata will be unimpeded. I have shown a preferred apparatus for carrying out my improved method but obviously I do not wish to be limited to the mechanism shown.

In the drawings,

Fig. 1 is a vertical, longitudinal, sectional view through an oil well showing a cleaning tool and packer in place.

Fig. 2 is a vertical, longitudinal, sectional view through an oil well and cleaner with an acid container in position for depositing the acid in the bottom of the well. I

Fig. 3 is .a vertical, sectional view through the acid container, and

Fig. 4 is a fragmentary'view of the lower end of the acid container, the associated parts being shown detached therefrom.

Referring now to the drawings:

1 designates a well provided with a foraminous lining 2 of usual construction. 3 designates a cleaning tool comprising a hollow tube having a screw 4 at its lower end and provided intermediate its ends with a packer 5. 6 designates an acid container aving an open end 7 provided with exterior screw threads 8. The threaded portion of the open end 7 is restricted as shown to receive an internally threaded collar 9, abo

provided with an opening 10. 11 designates wafers or discs preferably of zinc which may be secured between the end or" the container 6 and the inner face of the collar 9, as shown in Fig. 3. The container is also provided with a bail 12 having an eye 13 to receive a cable or cord it, as will be presently explained.

If there is an accumulation of para-fine, bitumen, asphalturn or other hydro-carbon at the wall or at the screen of the well, the well is first cleaned and then any oil which has an aflinity for the accumulation to be attacked may be introduced through the hollow tool 3 so as to enter the well through the openings 15-. The oil (for example, gasoline) will attack the or other hydro-carbon so as to dissolve it out or free it from the screen 2 or the walls of the well as the case may be. The oil may be introduced either hot or cold and in some instances pressure may be applied to force the oil against the. sides of the well, pressure to be maintained on account of the packer 5. The oil with its dissolved-out or loosened matter may then be removed and if lime is present, a suitable acid may then be introduced to attack the calcium, silicon or other accumulation present. The preferred method of introducing the acid is through the medium of the container 6 which is provided with the zinc wafers 1]. as a temporary bottom. It is desirable to introduce the acid into the bottom of the well and inasmuch as wells vary in depth, I have provided means whereby the acid may be lowered to the bottom of the well parafine, asphaltum' before being released. I prefer to use hydrochloric acid which readily attacks zinc and I prefer to have the zinc wafers or discs of such thickness that a given time will be required for the acid to eat through each disc. By way of example, each wafer may be designed to resist the acid for five minutes; therefore, if it requires five minutes to lower the receptacle from the top of the well to the point of discharge, one disc will be placed in the bottom of the receptacle. If ten minutes are required, two discs will be used; fifteen minutes, three discs, and so on. As the hydro-chloric acid eats away the discs it will flow out into the tool 3 and pass through the openings 15 to attack the accumulation present. As the lime, silicon or other accumulation is eaten away, the clogged Walls or screen will be relieved of the accumulation and the'oil from the surrounding strata may flow into the well unimpeded. The particular advantage of pro-' viding the container is that the acid may be applied locally in the well, thereby reducing the quantity to a small portion of that which would be required if it were .necessfiry to pour the acid from the top of'the we After the acid has a sufiicient time to act upon the accumulation, the well may be flushed out by a suitable fluid such as air, water or the like, after which the method will befinished.

In some instances, as for. example, in hard sand wells where the reticulated lining is not used, the acid container can be lowered directly into the well chamber 16 instead of into the cleaning tool 3.

\Vhat I claim and desire to secure by Letters-Patent is:

1. The method of introducing acid into a well which consists in confining an acid in a container having a wall, part of which will disintegrate under the action of acid, and l'owerin the container into the well before the wal part disintegrates. V

2. The method of introducing acid into a well which consists in providing an acid container having an opening through which the acid may escape, closing said opening by a wall which will disintegrate under the action of acid, the period re uired to disintegrate the wall being determined by the depth of the well, and lowering the container into the well before the wall part disintegrates.

3. The method of cleaning oil wells which consists in confining an acid in a container having a. wall, partof which will disin- Y tegrate under the action of acid, lowering the container into the well before the wall part disintegrates so as to locally apply the acid to the part of thelining to be attacked,

and then introducing aflush-ing fluid into the well adjacent to the part of the lining previously treated by the acid.

In testimony whereof I afiix my signature.

WILLIAM I F. MUEHL. 

